This is true
Anyone at or below sea level within 25-30 miles of a coastline is nuts to stay but many always do and they always will.
When Dennis was heading directly toward Mobile the Govenor ordered a mandatory evac of Mobile County and less than 10% left including the people really at risk.
You can't force people to leave but you can try to educate them to the danger and focus the evac efforts on the truly risky areas.
It would have interesting to see all those busses that were flooded deployed to give any poor or otherwise person the opportunity to leave.